I've had 350bhp on my stock clutch for a good 4 years now and no problems at all, touch wood. BUT....my driving style isn't fast, I don't rag it about and floor it at every opportunity, I don't race people away from the lights, I've never actually timed my 0-60mph time. I have a lot of mechanical sympathy I guess you could say. The car's 10 years old and on its original clutch.